Page 365 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

332 SECTION | III Nanoparticles, Radiation and Carcinogens

VetBooks.ir TABLE 19.4 Body System-Specific Manifestations Associated With Acute Radiation Syndrome (ARS)

Dose
Syndrome Associated Exposure Clinical Manifestations
Cerebrovascular $15 20 Gy (humans) Hyperthermia, ataxia, loss of motor control, apathy, lethargy, cardiovascular shock,
.80 100 Gy (lethal seizures, coma
dose in animals)
Pulmonary 6 10 Gy (humans) Pneumonitis within 1 3 months of exposure followed by respiratory failure,
pulmonary fibrosis, or cor pulmonale months to years later
Gastrointestinal $6 Gy (humans) Anorexia, nausea, vomiting, diarrhea with or without blood, loss of peristalsis,
10 100 Gy (lethal dose abdominal distension, dehydration, sepsis
for animals)
Hematopoietic $1 Gy (humans) Pancytopenia, hemorrhage, sepsis
2 10 Gy (lethal dose
for animals)
1
Cutaneous 3 50 Gy (humans) Bullae, blisters, hair loss, pruritis, ulceration, onycholysis
Source: Adapted from Rella, J.G., 2015. Radiation. In Hoffman, R.S., Howland, M.A., Lewin, N.A., Nelson, L.S., Goldfrank, L.R. (Eds.), Goldfrank’s
Toxicologic Emergencies (10th ed.) (pp. 1703 1712). McGraw-Hill Education, New York; von Zallinger, C., Tempel, K., 1998. The physiologic response of
domestic animals to ionizing radiation: a review. Vet. Radiol. Ultras 39(6), 495 503.

more detail in Table 19.4. Time to onset of vomiting and In domestic and exotic vertebrate animals receiving
kinetics of lymphocyte depletion have been used as the radiation therapy, side effects are generally categorized as
basis of triaging human radiation exposures. The gold acute effects and late effects (Kent, 2017). Acute effects
standard is analyzing the number of dicentric chromo- reported near the end of therapy or soon after include
somes in lymphocytes, which can be correlated to a mucositis and desquamation, usually resolving within
whole-body radiation dose (Rella, 2015). weeks. Examples of late effects seen after months or
The generalization that young, rapidly growing tissues years are fibrosis, necrosis, and new tumor formation.
are most radiosensitive was postulated by Bergonie and Acute radiation doses that are lethal to vertebrates are
Tribondeau (1906). In mammals this includes reproduc- generally lower than lethal doses in invertebrates. In a
tive germ cells, dermal and gastrointestinal stem cells, similar fashion, reproductive success in mammals is more
and erythroblasts (Sample and Irvine, 2011). Cattle stud- radiosensitive than in invertebrates, with fish falling
ied after the first atomic bomb test in 1945 were estimated somewhere in between. Various databases of radiation
to have received 1.5 Gy of penetrating whole-body radia- exposure and effects, exposure estimation and risk evalua-
tion and 370 Gy of beta radiation to the skin over the dor- tion models, and effects thresholds have been developed
sum (Brown et al., 1966). The animals developed and are reviewed in detail elsewhere (Sample and Irvine,
epilation and blistering 3 4 weeks later that healed with 2011). Most recently, the International Commission of
scarring after several months. Three years later, hyperker- Radiological Protection (ICRP) introduced a system of
atosis, epilation, depigmented hair, and other abnormali- Reference Animals and Plants (ICRP, 2009). By provid-
ties were still evident, and cows surviving $15 years ing radioisotope effects data for 39 elements in 12 species
developed squamous cell carcinomas in the previously- found in a variety of habitats (deer, rat, duck, frog, trout,
affected areas. Compared to adult cattle, calves with ARS flatfish, bee, crab, earthworm, pine tree, wild grass, and
develop more severe respiratory infections, diarrhea, and brown seaweed), exposures and effects in other animals
hemorrhage (von Zallinger and Tempel, 1998). can be estimated.
The LD 50/30 for birds ranges from 5 to 20 Gy for most
species (Woodhead, 1998), making them about as sensitive LONG-TERM IMPACTS OF RADIATION
to acute radiation exposures as mammals. A gradual
EXPOSURE IN ANIMALS
decline and subsequent recovery was observed in newly
hatched white leghorn chicks exposed to 2.25 Gy of Based on observations among human survivors of
gamma source radiation (Malhotra et al., 1990). In the Hiroshima and Nagasaki and Chernobyl cleanup
same study, single exposures of 15 day old chicks to workers, other adverse effects besides cancer can be asso-
6.6 Gy of gamma radiation was 100% lethal within 7 days. ciated with radiation exposure such as heart disease